Question

A gardener uses pipes to water his garden from the tank. For his entire garden he uses 6 pipes to water and it takes him 1 hour 20 minutes to completely empty the tank. Now if he uses only 5 pipes to water his garden, how long it will take him to empty the tank?

• A. 1 hour 30 mins
• B. 1 hour 36 mins
• C. 1 hour 45 mins
• D. 1 hour 55 mins

Answer 1

The correct option is B

1 hour 36 mins

Let the time required be x.

If the number of pipes used to empty the tank is increased, then time required to empty it will decrease.

Hence, the number of pipes and the time required are inversely related.

$\begin{array}{ccc}No.ofpipes& 6& 5\\ Timetaken\left(min\right)& 80& x\end{array}$

$\Rightarrow 6\times 80=5\times x\Rightarrow x=\frac{6\times 80}{5}=96mins\Rightarrow x=1hour36mins$